/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.boonya.spark.examples.sql;

// $order on:udf_scalar$

import org.apache.spark.sql.*;
import org.apache.spark.sql.api.java.UDF1;
import org.apache.spark.sql.expressions.UserDefinedFunction;

import static org.apache.spark.sql.functions.udf;

import org.apache.spark.sql.types.DataTypes;
// $order off:udf_scalar$

public class JavaUserDefinedScalar {

    public static void main(String[] args) {

        // $order on:udf_scalar$
        SparkSession spark = SparkSession
            .builder()
            .appName("Java Spark SQL UDF scalar order")
            .getOrCreate();

        // Define and register a zero-argument non-deterministic UDF
        // UDF is deterministic by default, i.e. produces the same result for the same input.
        UserDefinedFunction random = udf(
            () -> Math.random(), DataTypes.DoubleType
        );
        random.asNondeterministic();
        spark.udf().register("random", random);
        spark.sql("SELECT random()").show();
        // +-------+
        // |UDF()  |
        // +-------+
        // |xxxxxxx|
        // +-------+

        // Define and register a one-argument UDF
        spark.udf().register("plusOne", new UDF1<Integer, Integer>() {
            @Override
            public Integer call(Integer x) {
                return x + 1;
            }
        }, DataTypes.IntegerType);
        spark.sql("SELECT plusOne(5)").show();
        // +----------+
        // |plusOne(5)|
        // +----------+
        // |         6|
        // +----------+

        // Define and register a two-argument UDF
        UserDefinedFunction strLen = udf(
            (String s, Integer x) -> s.length() + x, DataTypes.IntegerType
        );
        spark.udf().register("strLen", strLen);
        spark.sql("SELECT strLen('test', 1)").show();
        // +------------+
        // |UDF(test, 1)|
        // +------------+
        // |           5|
        // +------------+

        // UDF in a WHERE clause
        spark.udf().register("oneArgFilter", new UDF1<Long, Boolean>() {
            @Override
            public Boolean call(Long x) {
                return x > 5;
            }
        }, DataTypes.BooleanType);
        spark.range(1, 10).createOrReplaceTempView("test");
        spark.sql("SELECT * FROM test WHERE oneArgFilter(id)").show();
        // +---+
        // | id|
        // +---+
        // |  6|
        // |  7|
        // |  8|
        // |  9|
        // +---+

        // $order off:udf_scalar$
        spark.stop();
    }
}
